I think I killed it...

[misterp]

NONE.....TM is bad when you have a shift kit

Wrong - adaptive shift timing is bad when you have a shift kit installed; torque management is fine. It's the adaptive shift timing tables that will attempt to slow the perceived shift speeds between gear changes.

 

Mr. P.

[12'SROCK]

Wrong - adaptive shift timing is bad when you have a shift kit installed; torque management is fine. It's the adaptive shift timing tables that will attempt to slow the perceived shift speeds between gear changes.

 

Mr. P.

 

 

is that the same as shift timing?

[misterp]

Aha. So is the "NO MORE than 2 washers in the 2nd accumulator cup with the Transgo Kit unless you have fully hardened internals" is the only manner of taming the 1-2 shift? Or are there other PCM settings that can help with this also?

When my trans was built the first time the technician who did so installed 3 washers in the 2nd accumulator cup without my knowledge; the trans banged into 2nd all the time and when I asked him about it he assured me the behavior was typical and would not be damaging in the long-term. Well after 18-mos the low-speed banging that came from that accumulator setup had shredded the 2nd clutches (not burned, shredded) and finally shattered the aluminum input drum. You have to remember that aluminum work-hardens, so months of hammering shifts will eventually make it brittle enough in the splines to grenade, as I learned after the fact. And it's hard to believe that one washer will cause this heartache but it can.

 

The PCM (or TCM) cannot make enough operating changes to work around a poor shift kit; in fact if your hardware isn't right it will only confuse the computer into making poor shift pattern decisions. Basically what you want is the PCM shift pressures table to remain stock and manipulate the shift timings and tw mgmt tables, and the tq mgmt really does tame the shift a lot by pulling timing during the shift window.

 

Mr. P.

[12'SROCK]

When my trans was built the first time the technician who did so installed 3 washers in the 2nd accumulator cup without my knowledge; the trans banged into 2nd all the time and when I asked him about it he assured me the behavior was typical and would not be damaging in the long-term. Well after 18-mos the low-speed banging that came from that accumulator setup had shredded the 2nd clutches (not burned, shredded) and finally shattered the aluminum input drum. You have to remember that aluminum work-hardens, so months of hammering shifts will eventually make it brittle enough in the splines to grenade, as I learned after the fact. And it's hard to believe that one washer will cause this heartache but it can.

 

The PCM (or TCM) cannot make enough operating changes to work around a poor shift kit; in fact if your hardware isn't right it will only confuse the computer into making poor shift pattern decisions. Basically what you want is the PCM shift pressures table to remain stock and manipulate the shift timings and tw mgmt tables, and the tq mgmt really does tame the shift a lot by pulling timing during the shift window.

 

Mr. P.

 

 

so me being RWD with the HD-2 kit, billet servos, aluminum acc piston, no TM, zero'd out shift times is bad?

[misterp]

is that the same as shift timing?

Yes. The GM Gen-3 & 4 computers' shift timings tables give the target shift times, and the PCM will modulate pressure and engine timing (to weaken the motor) to match the numbers in the table. So, if you install different hydraulic valving and springs in the valve body (aka shift kit) then you are physically changing the shift timing from 3-4 tenths of a second to like 2-tenths (or less) but if you leave 0.3 or 0.4 seconds in the shift timings tables the PCM will "slip the clutches" to enforce the longer pre-programmed shift window. = BAD.

 

Torque management has nothing to do with the transmission - it is ONLY and I repeat ONLY an engine ignition timing mechanism, it makes the motor weaker during certain operating situations. Torque management does nothing to change shift pressures, shift timing, etc - the tranny will still do the same shift behavior; what is different is that the shift is happening with less power entering the torque converter, that's all. Other situations where the PCM will pull timing is attempting to brake stall, and WOT launches, and in Vettes when the traction control circut is tripped - these situations don't have anything to do with the transmission, just the PCM's perceived need for reduced engine power.

 

Mr. P.

[CaliChevyV8]

Gettin deep

[misterp]

so me being RWD with the HD-2 kit, billet servos, aluminum acc piston, no TM, zero'd out shift times is bad?

OK I think I'm getting confusion - the recipie is simple:

 

1) install shift kit of your choice to meet the requirements of the vehicle;

2) zero out the entire shift timings table, all of it - you are telling the PCM that shift timings are determined by the parts in the valve body and to not butt-in to the tranny's operation;

3) depending on the clutch/servo setup and hard parts used decide on a Tq Management strategy and program that in the PCM (or TCM, Gen-IV);

4) Drive

 

If you have no idea what kind of Tq Management settings you want/desire then what I would do is go ahead and zero-out torque management and see what the 1-2 shift behavior is like at low throttle, we're talking like a 10 mph upshift as if you were cruising the walmart parking lot and it kicks into the next gear - if you can feel that low throttle 1-2 shift "kicking" then you need to re-address the 2nd accumulator design in your shift kit and get it right. Several options to do this is changing washer config (transgo kit) or spring config (superior) or slight de-tuning of the force motor calibration screw (no more than 1/8th turn). OTOH if the 1-2 shift isn't hard enough then your options are to increase base shift pressures table in the PCM (preferred) or increase overall base tranny line pressure across the board by adjusting the force motor calibration screw (a lot of guys do this, I don't like the thought of it though).

 

Mr. P.

Edited August 15, 2007 by Mr. P. (see edit history)

[CaliChevyV8]

I understand, I'll just wait and see how that 1-2 shift is when I get it all done. I remember a long time ago when I used to have a pcmforless tune it used to kick hard in to second and it would piss me off. Glad to know there is a recipe for it if it happens again after these mods.

 

Oh and as always thanks for all the great info P, I appreciate it

Edited August 15, 2007 by CaliChevyV8 (see edit history)

[misterp]

I understand, I'll just wait and see how that 1-2 shift is when I get it all done. I remember a long time ago when I used to have a pcmforless tune it used to kick hard in to second and it would piss me off. Glad to know there is a recipe for it if it happens again after these mods.

 

Oh and as always thanks for all the great info P, I appreciate it

Sorry to help from afar - if I were closer I'd be happy to give a hand.

[12'SROCK]

OK I think I'm getting confusion - the recipie is simple:

 

1) install shift kit of your choice to meet the requirements of the vehicle;

2) zero out the entire shift timings table, all of it - you are telling the PCM that shift timings are determined by the parts in the valve body and to not butt-in to the tranny's operation;

3) depending on the clutch/servo setup and hard parts used decide on a Tq Management strategy and program that in the PCM (or TCM, Gen-IV);

4) Drive

 

If you have no idea what kind of Tq Management settings you want/desire then what I would do is go ahead and zero-out torque management and see what the 1-2 shift behavior is like at low throttle, we're talking like a 10 mph upshift as if you were cruising the walmart parking lot and it kicks into the next gear - if you can feel that low throttle 1-2 shift "kicking" then you need to re-address the 2nd accumulator design in your shift kit and get it right. Several options to do this is changing washer config (transgo kit) or spring config (superior) or slight de-tuning of the force motor calibration screw (no more than 1/8th turn). OTOH if the 1-2 shift isn't hard enough then your options are to increase base shift pressures table in the PCM (preferred) or increase overall base tranny line pressure across the board by adjusting the force motor calibration screw (a lot of guys do this, I don't like the thought of it though).

 

Mr. P.

 

 

thanks "p"

[Fallen.One05]

Sorry to help from afar - if I were closer I'd be happy to give a hand.

 

...... so you can help me with mine.. right?

[CaliChevyV8]

They are more than likely gonna flash your pcm unless you tell them otherwise. thr RPO code for the 4L70E is M70...it would say it in your glove box

 

I do have the 70E! I checked my glove box and it said M70 on the code list.

[CaliChevyV8]

OH YEAH! heat is the transmissions worst enemy. its only $110 shipped for the tru-cool max cooler

 

Is there any other higher end tranny cooler kits you guys know of?

[misterp]

...... so you can help me with mine.. right?

Sure can!

[CaliChevyV8]

I got my truck back! And I can tell my tune is back to stock I'm just happy I finally have it back though. Transgo is on order and the 2nd and 4th servo. 2400 stall is comin too.

 

I wish they had a custom fit kit for a tranny cooler for our trucks...Sounds like a biatch locatin all the hoses and fittings and stuff.